1. Field of the Invention
The present invention relates to an object detection apparatus having a zoom function, and a control method for the object detection apparatus.
2. Description of the Related Art
Some image capturing apparatuses such as digital cameras have an optical zoom function of driving a zoom lens and an electronic zoom function of enlarging part of a captured area. In recent years, it has become possible to perform shooting from super-wide angle to super-telephoto with a single lens thanks to improvement in performance of a zoom lens, and to obtain an image having a sufficiently high resolution even at a high enlargement magnification thanks to an increase in number of pixels of an image sensor.
Japanese Patent Laid-Open No. 2012-60595 proposes a function called a framing assist zoom function (FA zoom function) as a function of immediately capturing an object again when the object moves out of a frame. When the start of the FA zoom function is instructed, an apparatus disclosed in Japanese Patent Laid-Open No. 2012-60595 can zoom out to move the zoom position in the wide angle direction. When the end of the FA zoom function is instructed, the apparatus can zoom in to the zoom position when the start of the FA zoom function was instructed.
On the other hand, there is known a so-called auto zoom function as a function in which a camera detects an object within a screen, and automatically changes a zoom position in accordance with object detection information. Japanese Patent Publication No. 6-5912 (Japanese Patent No. 2052653) discloses a method of zooming out to move the zoom position in the wide angle direction when an object reaches the limit position of a specific area within a screen. Japanese Patent Publication No. 6-5912 also proposes a method of zooming in to move the zoom position in the telephoto direction when an object stays in the central portion of the screen.
According to Japanese Patent Publication No. 6-5912, however, depending on the moving speed of an object to be captured, zoom operation start conditions, a zoom change amount, and the like, the auto zoom function may immediately zoom in based on the position of the object when the object moves close to the center of the screen in a zoom-out operation, and may immediately zoom out based on the position of the object when the object moves close to the peripheral portion of the screen in a zoom-in operation. That is, a hunting phenomenon may unwantedly occur in which a zoom-out operation and a zoom-in operation are repeated. As a result, a photographer may be annoyed, or may miss a shutter chance due to the operation.
The above-described FA zoom function performs a zoom-out operation or zoom-in operation in accordance with an operation by the photographer. To improve the convenience of the photographer, the FA zoom function is assumed to automatically perform a zoom operation in accordance with the state of the object. In this case, it is required to suppress the above-described hunting phenomenon in order to quickly adjust an angle of view.